engleski

Assessment of the out-of-plane earthquake resistance of reinforced concrete frame structures with masonry infill walls containing openings

Multi-storey buildings are generally loaded by inter-storey drift and inertial forces during an earthquake event. The seismic event excites the structure in an arbitrary direction. When observing the structure’s plane, the load can be divided into in- and out-of-plane forces. The in-plane forces by their nature are inter- storey drift ones, while the out-of-plane ones are both inter-storey drift and inertial. By examining the literature, it was determined that most of the experiments within the out-of-plane field of research were conducted with inertial, less with dynamical and only two using inter-storey drift force methods. The analytical models for calculating inertial, load-bearing capacity found within the literature were tested against various experiments. From the analysis, their limitations and best fitting equations were derived. Furthermore, from the gathered experimental data, it was observed that the static and quasi-static inter-storey drift force methods have more similarities with dynamical tests than the inertial methods. Aside from the limited out- of-plane inter-storey drift studies, none of which were done with RC frames ; the field had few and conflicting studies with openings. The research laid in this thesis answers just that ; the influence of infill walls with and without openings on RC frames subjected to drift driven in- and out- of-plane loads. This thesis was built upon the existing one covering in-plane cyclic, quasi-static load. The experimental contribution of this thesis included out-of-plane cyclic, quasi-static inter- storey drift load on frames with and without infill walls and openings, along with the out-of-plane bending test of masonry walls. The same materials, techniques, and equipment were used for all three experiments. Openings were varied in their type (window and door) and position (centric and eccentric), while the out-of-plane bending test had load parallel and perpendicular to bedjoints. The out-of-plane drift force tests showed that the infill wall and the frame moved as one and that the infill had an insignificant contribution to the overall behaviour of the frame, i.e. the behaviour of the bare frame model was similar to other infilled ones. Yet, the infill wall suffered considerable damage, mostly by separating rows of blocks in bedjoints. This pointed out that the frame to masonry interaction was one-sided, i.e. only the frame transfers displacements and damages the infill wall. All the out-of-plane drift force test outcomes are consistent with the literature’s dynamical and drift force studies. After the experiments were conducted, computational models were developed and calibrated against them. The calibration yielded the factors that govern the simulated behaviour of the models. For the in-plane studies, it was the interface (gap) and concrete material model, while for the out-of-plane bend tests for the masonry walls, it was both the interface and masonry material models. Thus, it was concluded that the masonry material model had little influence on the overall behaviour of in- plane simulations. Afterwards, the research was extrapolated to combine in- and out-of-plane loads into a simultaneous action. The combination was described by the angle of the resultant force α. The simulations tested 20 configurations from a bare frame, infill wall with or without openings with their area ratios ranging approximately 0.1, 0.2 and 0.3 in relation to the infill’s area. Also, they were positioned centrically or eccentrically, loaded from left or right under nine angle positions (0 to 90°, i.e. from in- to out-of- plane). Overall, 180 models were tested, with which interaction curves and equations for estimating load- bearing capacity based on that of the in- plane ’s bare frame were derived. The estimating equations showed a good fit with the data from the simulations.

RC frames; masonry infill walls; influence of openings; experimental and computational approach; out-of-plane drift force load; simultaneous in- and out-of-plane action; simultaneous in- and out-of-plane interaction curves; simultaneous in- and out-of-plane load-bearing equation

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